Antidepressant paroxetine use linked to risk of birth defects

"Antidepressant 'does increase your baby's risk of birth defects if taken in first 12 weeks of pregnancy','' the Mail Online reports.

A study of previous data suggests the commonly used antidepressant paroxetine may increase the risk of defects by around a quarter.

The researchers pooled data from 23 studies which compared women who took paroxetine during the first three months of their pregnancy, with women who did not. It found that the small overall risk of birth defects was 23% higher. This takes the overall risk to approximately 3.69% for women who had taken paroxetine at this time.

Based on the type of studies included, we cannot be sure the effect was due to the drug or other factors, such as the woman's depression or other factors linked to it.

Depression during pregnancy is more common than many people realise and can be serious, affecting both mother and baby. Experts have warned that pregnant women with depression should not stop taking antidepressants without talking to a doctor first.

If you are taking paroxetine and have just found out you are pregnant, you should contact your GP as soon as possible to discuss treatment options.

Where did the story come from?

The study was carried out by researchers from the University of Montreal in Canada and was funded by the Fonds de la Recherche du Québec – Santé and the Réseau Québécois de recherche sur les médicaments.

One of the researchers is an advisor to women taking legal action over antidepressants and birth defects, so has a conflict of interest.

The Mail Online's story appears accurate and responsibly included cautions and advice from experts not involved in the study. However, the headline over-stated the certainty of the results.

What kind of research was this?

This was a systematic review and meta-analysis of previously published research. This is a good way to establish the state of knowledge about a subject. However, a meta-analysis is only as good as the studies available.

The average risk of major birth defects is 3% and for heart defects is 1%. The researchers wanted to see if use of paroxetine increased this risk.

What did the research involve?

The researchers looked for all the studies published on the use of paroxetine during the first three months of pregnancy, which included birth defects as an outcome, using the EMBASE and MEDLINE databases.

They pooled the results to find out whether paroxetine taken at this time had an effect on the chances of babies being born with any major congenital birth defect, and of heart defects in particular.

They excluded studies which did not report on birth defects, or where the study grouped together women who had taken any type of selective serotonin reuptake inhibitors (SSRIs) antidepressant along with paroxetine, and the results could not be separated.

They looked at whether the type of study or the source for the data used in the study made a difference to the results. They also used statistical techniques to see whether the results could have been affected by so-called publication bias – where only positive studies are published.

They tried to allow for the possible effects of depression by looking separately at the results of trials which included women with depression taking paroxetine, compared to women with depression not taking paroxetine. However, there were few trials where women with depression had no treatment, so most groups compared women taking paroxetine with women on national registers who were not taking the drug, most of whom would not have been depressed.

What were the basic results?

The researchers found 23 relevant studies. The results showed women who had taken paroxetine in the first three months of pregnancy were 23% more likely to have had a baby with any major congenital defect (odds ratio [OR] 1.23, 95% confidence interval [CI] 1.10 to 1.38). They were also 28% more likely to have a baby with a major heart defect (OR 1.28, 95% CI 1.11 to 1.47).

The researchers said that restricting the results to those only including a control group of women with depression who didn't take paroxetine made little difference to the results. Studies which used data from advice lines for people concerned about the effects of drugs in pregnancy found higher risks compared to those using administrative sources, probably because people were more likely to call the advice lines if they had experienced a problem or were at higher risk of birth defects.

How did the researchers interpret the results?

The researchers said their results demonstrated "a constant trend in showing an increasing risk of major malformation and cardiac malformations," for women taking paroxetine.

They questioned whether the benefits of the drug for depression in pregnant women outweighed the risks: "Given that the benefit of using these medications during pregnancy is debatable, any increase in risk is significant," they said.

Conclusion

The big question for pregnant women with any type of illness is always whether the benefits of treatment will outweigh any possible risk of harm to their babies.

The question of whether paroxetine can cause birth defects has been under discussion since 2005, when a small study suggested an increased risk of heart malformations. Since then, there have been many studies with conflicting results.

This systematic review brings together the latest research and pools the results to come up with a best estimate of the risk of birth defects linked to paroxetine. The strengths of the study are that it was a systematic review, so should have included any relevant research, and that the researchers analysed the data in different ways to look for potential biases or factors that could have skewed the results.

They found a small increase in the risk of women's babies having had any major birth defect, and heart defects specifically, if they'd taken paroxetine, compared to women who had not taken the drug. However, this does not mean that paroxetine caused the problem.

The review has limitations. Although most of the studies included adjusted their results to take account of a possible effect of depression on birth defects, we don't know how accurate these adjustments were. Other important factors may not have been included that could have affected the results, such as other health problems, poor diet, alcohol or tobacco use.

So where does that leave women who need treatment for depression during pregnancy? It is important to seek help, because depression can be serious for mother and baby. Not all treatments for depression include medication, and for pregnant women with mild depression, talking therapies may be more appropriate.

However, for some women, antidepressants may be needed. This study found that the overall risk of major birth defects remains low, at less than 4% for women taking paroxetine during the first three months. Women should discuss their options with their doctor, midwife or psychiatrist to decide what is best for them.

If you are pregnant and taking antidepressants, don’t stop taking them suddenly. Talk to your doctor if you are worried. Stopping antidepressants suddenly can be dangerous, as this can trigger a range of withdrawal symptoms, some of which may be harmful to your pregnancy.